The present invention relates to rotary variable differential transformers (RVDT's) and in particular to cross talk compensating RVDT's.
RVDT's are used in control and measurement devices to encode a displacement into an analog electrical signal. In the main, the RVDT's consist of one or more primary and secondary coils as part of the stator assembly, a rotor and a stator. A shift in the position of the rotor relative to the stator produces a change in the magnetic coupling between the primary and secondary windings and thereby causes a change in the output voltage measured across the secondary when an A-C signal is applied to the primary.
One of the major uses for RVDT's is in control and guidance systems (for example, for aircraft). In such applications it is common to provide multiple RVDT's on a common shaft one acting as a backup for the other. In such applications each RVDT is excited at a different frequency. The use of different frequencies for the different RVDT's produces a problem of cross talk between the RVDT's resulting from the leakage flux from one RVDT effecting the output voltage of the other RVDT.
In view of the above, it is the principal object of the present invention to provide an improved multi-unit RVDT in which cross talk between adjacent units is cancelled.
A further object is to provide such an RVDT in which the cancellation is attained without effecting the output of any of the individual units.
Still further objects and advantages will become apparent from the following description of the invention.